1. Field of the Invention
The present invention relates to an innovative structure for a light emission diode (LED), and more particularly to an innovative LED which can emit white color light with much better uniformity, color quality, and a larger projection angle than conventional LEDs.
2. Description of the prior art
At present, the LED is popularly employed in computers, communication apparatus, and electrical appliances. Generally, colors of light emitted from a LED are red, green and blue, but as a LED, it seldom generates a white light owing to the particular difficulty in controlling the color display of a white light. For example, a white light may appear from a LED element containing three primary color factors of red, green and blue (R.G.B.) when those individual colors are emitted simultaneously. But such a synthetic white light composed of R.G.B. three primary colors will not be uniformly and purely emitted because the values of current generated by three LED crystal chips of R.G.B. colors are different from one another resulting in difficulty of controlling the color display of a white color.
FIG. 1 illustrates a known method of generating a white light from a LED crystal chip published in Japanese Patent gazette 7-99345 in which a layer of yellow fluorescent material is applied on a LED crystal chip which emits a blue light. A synthetic white light may be emitted from this LED chip, but there is a problem of controlling the thickness of the fluorescent material layer on the LED which leads to non-uniform distribution of the white light produced. If the layer of the yellow fluorescent material is too thick, the synthetic light color will turn slightly yellow. On the contrary, if the layer of the yellow fluorescent material is too thin, the synthetic light color will tend to be slightly blue. Moreover, if the yellow fluorescent material is applied too excessively around the periphery of the LED chip, the resultant white light emitted from the LED when projected onto a white paper, produces a yellow colored ring which prevents the light projection angle of the LED from being wider.